Lenskart - Charging over and above the membership fees

I purchased Lenskart Pro membership which includes First Pair Free along with Anti Glare Lenses as promised by them. But when we try to add anti glare lenses to the Pair, it asks **/- extra over and above the membership fees. When contacted customer care, they said that this is the tax that they are collecting, But it is to be noticed that it is nowhere mentioned that it is the tax which is being collected, it clearly states that it is price for lens package.